The United Nations’ World Health Organization (WHO) has expressed concern over a dramatic rise in the incidence of “transplant tourism,” in which wealthier medical patients — usually from First World countries — travel to poor countries for transplants from people who have been persuaded to trade their organs for money.

According to Luc Noel of the WHO’s health technology and pharmaceuticals unit, the prevalence of transplant tourism has increased over the past 10 years to the point where it accounted for five to 10 percent of worldwide kidney transplants in 2005.

Poor people in countries such as Egypt, Pakistan and the Philippines are commonly convinced by organ brokers to sell their body parts.

“There are villages that are in the poorer parts of Pakistan where as many as 40 to 50 percent of the population of the village we know only has one kidney,” said Farhat Moazam of the Sindh Institute of Urology and Transplantation in Karachi, Pakistan. While organ donors may be promised as much is 150,000 rupees ($2,500), she said, the amount they see may be drastically lower once brokers’ fees and medical costs are deducted.

In addition, many such donors do not receive the needed follow-up care after their major surgery, which often leads to serious health complications.

According to Jeremy Chapman, a doctor at Westmead Hospital in Sydney, Australia, advances in surgical techniques have led to an explosion in the demand for organ transplants. This, in turn, has led to a shortage of organs, most of which are donated by people only after their deaths. If a living relative is not available to donate the needed organ, many people are now turning to other countries to find what they want.

“The wealthy, in search of their own survival, will sometimes seek organs from the poor,” Chapman said, summing up the troubling dynamic.

In response to this trend, the WHO has recommended stricter international rules on organ donation and transplantation.